國立暨南國際大學 101 學年度第一學期小考試卷

1. (10%) Determine whether the following code is correct or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   
   // Bubble Sort
   #include <iostream>
   
   int bsort1(int A[], int n)
   {
       int i,j,temp;
       bool sorted;
       for (i=n-1; i>0 ; i--)
       {
           sorted = true;
           for (j=0 ; j<i ; j++)       
               if (A[j] > A[j+1])
               {
                   temp = A[j]; A[j] = A[j+1]; A[j+1] = temp;
                   sorted = false;
               }       
           if (sorted)
               return n-i;
       }
       return n-1;
   }
   
   int main()
   {
       int a[] = { 8, 1, 3, 2, 5, 4, 6, 7 };   
       int size = sizeof(a) / sizeof(a[0]);
       int n = 0;
       n = bsort1(a, size);
       std::cout << "It takes " << n << " pass"
           << (n>1?"es":"") << " to sort the sequence.\n";   
       return 0;
   }
   
   
   
2. (10%) Determine whether the following code is correct or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   
   // Array of Pointers to Functions
   #include <iostream>
   void print_array(int a[], int n)
   {
           for (int i=0; i<n; i++)
               std::cout << a[i] << ' ';
           std::cout << '\n';
   }
   
   int cmp1(int a, int b)
   {
       if (a < b)       
           return -1;       
       else
           if (a == b)
               return 0;
           else
               return 1;
   }
   int cmp2(int a, int b)
   {
       if (a > b)       
           return -1;       
       else
           if (a == b)
               return 0;
           else
               return 1;
   }
   
   int bsort(int a[], int n, int (*pfun)(int a, int b) )
   {
           int i, j, temp;
           for (i=n-1; i>=1; i--)
               for (j=0; j<i; j++)
                   if (pfun(a[j] , a[j+1]) > 0 )
                   {
                       temp = a[j];
                       a[j] = a[j+1];
                       a[j+1] = temp;
                   }
           return 0;
   }
   
   int main()
   {
           int a[] = { 7, 3, 5, 1, 6, 4, 2 };
           int size = sizeof(a) / sizeof(a[0]);
          
           int (*pfun[2])(int, int) = { cmp1, cmp2 };
           for (int i=1; i>=0; i--)
           {
               bsort(a, size, *(pfun+i));   
               print_array(a, size);
           }
           return 0;
   }